Junction box for underfloor conduit and duct systems for cellular floors



Nov. 17, 1959 R. JoHNsoN 2,913,136

JUNCTION Box FOR uNDERFLooR coNnuIT AND DUCT SYSTEMS FOR CELLULAR FLOORS Filed Jan. 29, 1957 az as f 8 1 '1616 70 17"'.3A a f 1:92a

y ATTRNE YS the concrete is poured.

JUNCTION BOX FOR UNDERFLOOR- CONDUIT AND DUCT SYSTEMS FOR CELLULAR FLOORS Robert Johnson, Edgeworth, Pa., assignor, by mesnel asisignments, to H. K. Porter Company Inc., Pittsburgh, Pa., a corporation of Delaware Application January 29, 1951, serial No. 637,032 l 4 claims. (ci. zzo-3.3)

. cells over which concrete is poured. The floor cells conf tact with one another and provide an impervious structure for supporting the concrete before it hardens. The

lwiring are of round cross section.

2,913,136 Patented Nov. k17, V1959` ICC Figure 3 is an end view of the junction box shown in Figure 1 with the duct and conduit removed.

Figure 1 shows a junction box 10 having a bottom 12 and side walls 14. There is at least one opening 16 shaped to receive an underfioor duct 18 which is generally rectangular in cross section with the corners rounded.

There is also at least one opening 20 shaped to receive an end of a conduit 22. The conduits for electrical In order to4 provide a stop or abutment for limiting the extent to which the 'duct 18 and conduit 22 are inserted into the openings 16 and 20, respectively, there is a shoulder 24 in the opening 16 and a corresponding shoulder26`in the opening 20. p

Means 'are provided for preventing displacement of the duct 18 andv conduit 22 from the junction box after they have been assembled with the junction box. In the pre-Y cells constitute the lower part of the nal floor structure'. l

The cells are placed in parallel relation and some types are constructed so that their side walls converge toward the upper part of the cell to a juncture with the top wall of the cell which is substantially narrower than the bot'- tom 'of the cell.

This leaves space between the cells for concreteand it also results in the top walls of the cells being 'spaced from one another. The concrete is poured to a substantial depth above the top walls of the cells, and ducts and conduits for underoor electrical systems are located in the concrete above the tops of the cells. v, In floors of cellular construction, it is a common prac- 4tice to use the Hoor cells as conduits for electrical con-v ductors and header ducts are placed at right' angles to the oor cells, and immediately above the oor cells, for the passage of wires .in directions at right angles tothe length of the oor cells. Electric outlet fittings are con"- nected with the header ducts at desired locations before Various other types of underoor electrical' system's have been used with concrete oors, and junction boxes of different kinds have been devised forY use with' the different kinds of underoor systems. It is an object of this invention to provide an improved junction box which can be used for combining under- I object of the invention to provide an improved junction box which is more Versatile in the uses to which it can be put in underfloor electrical systems; and it is still an: other object of the invention to combine the improved junction-box with a cellular floor construction in a man ner toconnect the interior of the oor cell with the different types of underoor electrical systems which may be embedded in the concrete above the cells. i

Other objects, features and advantages of the invenl tion will appear or be pointed out as the description proceeds. y

In the drawing, forming a part hereof, in which like reference characters Vindicate corresponding parts in all the views; 1 f

Figure 1 is a top plan view, partly broken away and n section, of a junction box 'embodying 'this invention; the section being on the line 1--1 of Figure 2;

Figure 2 is a sectional view through the junction box, 0n the line 2 2 of Figure l, and with the junctionbox located in assembled relation with a oor cell of a cellular flooring construction; and .I

erred construction`,"this means consists of set screws.' A set screw 28 (Figure 2) threads through the top Wall of the opening 16 and bears against the top of they duct 18. A corresponding set screw 30 (Figure 3) threads through the top wall of the opening 20 and into contact with the conduit which is inserted into this opening.

The junction box 10 has a plurality of openings at different locations around its perimeter for receiving ducts and conduits extending in different directions. In the construction illustrated, there are four openings' 16 for receiving ducts and there are two openings 20 for receiving conduits. This construction is merely illustrative of a junction box having a plurality of openings for ducts and a plurality of openings for conduits.

The junction box 10 rests on a top wall 34 of a floor cell 36. The cellular oor construction is best shown in Figure 2. The floor cell 36 has side walls 38 which converge toward their upper ends where they join the top wall 34. The bottom of the oor cell 36 is indicated by the reference character 40, and this bottom 40 has its side edge in contact with the opposite edge of the bottom of a next adjacent floor cell 42 which is of similar construction to the oor cell 36 and parallel to it. It will be understood that there is another corresponding ll'oor cell along the left edge of the oor cell 36 and that the entire cellular floor is made up of a group of such parallel cells over which the concrete is poured to make the final oor.

The junction box 10 has an elongated opening 46 in its bottom wall. This elongated opening 46 has a width approximately equal to but slightly less than the width of the top Wall 34 of the oor cell; and the opening 46 has an edge portion 48 which turns downwardly through an angle of preferably at least 90 to provide a vertical extent for the edge portion 48 within an opening 50 through the top wall 34 of the oor cell.

The purpose of this downwardly extending edge portion 48 is to provide guide means for preventing the insulation of a conductor 52 from striking the edges of the opening 50 since'the edges of this opening 50 are likely to be sharp enough to damage the insulation of the conductor when it is being pulled through the passages of the electrical system. The lower edge of the downturned edge portion 48 is preferably rounded so that it cannot damage insulation of any conductor which rubs across it while being pulled through the system.

The bottom of the edge portion 48 can be effectively rounded and smoothed'when the junction box is manufactured at the factory, but the edges of the opening 50 5 are Ioriginally manufactured because the location of the desired openings in thefloor cells are not known to the manufacturer, and it would not be practical to try to reserve particular Iiloor cells for particular locations when constructing a cellular floor.

The opening 46 :can be made narrower than. shown, but it cannot be made wider 'thanthedopwall 34 offthe floor cell. In order-to increase the open area andfthus provide more spacefor.reachingdown-into a floor-cell to pull additional wires or conductors, the opening 46.'v is made substantially longer 'than itis wide, and the length of this opening 46is preferably as great as practicalY within the limits of'the box diameter.

"In the construction shown, the elongated opening `46 cannot be made equal to thefull ,diameterof theinterior of thebox'because thel boxisequipped with other openings 55 for fastening means, preferably. screws 56, for attaching thebox to vthe top vwall of the'oorcell. Y'These screws '56 are within the contines of an area which ,is directly overthe. top wallof the Yfloor-cell; and withthe opening 46 almost as wide as the top wallof theiioor cell throughout most of-theflength of the opening .46, it .is necessary to have the opening 46 of reduced width toward the ends where Ithe screws` *56 are-located.

In the preferred construction, the ends Vof the `opening 46 are rounded andthe screws V56.are'locatedadjacent to the elongated opening-46 at-.locations where thisopening is of reduced width. These 'screwsf''are .preferably self-tapping screwsjso that it is merely :necessary tofdrill holes through .the top wall of the floor fcell `and then drive 5the vscrews 56 vinto :these holes, the threads .being cut by thescrews in the top Wall of thecellas .4t-he. screws advance. "Other means for attaching the .junctionnbox to-thefloorcell canfbeused and ,the.screwsf56 are merely representative l.of such means.

JTh'etop lof the junction box'is closed' bya cover .plate 60 which ts within an adjusting'ring62. ".There is Van inwardly extending 'ange `64 in. position to --support -the cover plate60 with its -top surface ofthecover plate-sub stantially llush with the top edge -of the Aadjusting ring 62. AV gasket V66 is locatedbetween ther-cover plate 60 and the top surface of the inwardly extending flange 64. The cover plate60 is attached tothe adjusting ring 62 by screws l68 whichthreadinto theflange 64 atlocations where the flange is made slightly widerV to receive vthe screws 68. These screws 68-have Atheir-.heads countersunk in the cover plate 560.

`The adjusting ring 62 is attached to thef junction box 4 10 by screws A70 which extend through slotsw71 (Fig. Vl)

in the ange 64 and thread into lugs72 (Fig. 2),.project- ,ing` inwardly from the side walls of .the junction'box at angularly spaced regions around the-circumferential=ex tent of the junction'box. Thesescrewsi't) `havelheads of larger diameterthan the :width of the 'slots 71, and -these heads of thcscrewsf70 extend through openings in the cover plate '60 and have their upper ends flushwith the top surface of the cover plate. This makes the screws 70 accessible'from above the boxfeventhough theY cover is on, for adjusting the ring .62. ilange-64is-of increased'width at the regions `wherefthe flange receives the screws 70.

. AEach of fthe screwsf70 isof .reduced rdiameter where ispasses through theslot 71.andfthere.is.a shoulder 73 immediately below the slot where the'screw .70.-again increases to its full diameter. V'I'he diameter of: this shoulder is greater than the .width of thefslot '-71. Rotation-.of any one-f the screws '70 in a, direction Ato ycause it to. rise with respect to thelug 72, therefore, .brings the shoulder 73 .up against the underside of vtheliange .64.and-raises the adjusting ring 62. Conversely, rotation ofthescrew 70 inthe oppositedirection. lowers theadjusting-ring 62.

' The screws 70 are held -against'displacement lengthwise of -the slotsl 71 by retaining clips 74 (Fig. l). Each of these clips 74 is of spring material andk has a U-shaped end that receivessthescrew and .thatsnaps around the Y. reducedfdiametenpor'tion of the `screw above. theshoulder 4 73. The clip 74 has a tab 76 at its inner end extending at right angles to the U-shaped portion and upwardly into a notch 77 (Fig. 1) inthe front face of the lug 72.

In order to level the adjusting ring 62, and to vary its height to make the top surface of the cover plate 60 ush with the screed line of theA concrete floor, leveling screws 70 are provided at three angularly spaced regions around the circumferenceof the .junction box.

lThe junction box '10 yis kpreferably '-.made ein two parts, as best shown in Figure 3. There is a lower part 81 and an-upper part 82. .These parts. joinV along a division surface 83. There are projections "SSAon-thelower part S1 below corresponding projections 87 on the upper part 82. The parts" 81 and 82`are connected together 'by screws 89 which extend freely through openings in the projections 87 and thread into openingsfin the projections 85.

In the construction illustrated, there are four such screws 89 for holding the parts of the junctionbox .togetherand these screws are .preferably located neanthe set screws `3`0 which secure the ducts 11S toithe .junction box.

Thelpreferred embodiment of 'the invention has'been illustrated and described, but changes and modifications can be made,` and some Vfeatures can beused in 'different combinations without departing from'the inventiongals defined in the claims.

1. "An underoor 'duct system Yincludinga junction'y box comprising bottomand sidewalls, there being openings in thesidewalls'shaped to receive ends loflducts, the bottom of the box having an elongated openingthereimcellular o'oringthat'has longitudinally extending and parallel cellseach of`which has a top wall of predetermined width spaced from the corresponding'top walls of the next adjacent cells, the 'box being supported vby the' top wall of one of the cells which has an opening in said top wall elongated inthe direction 'of extent of the cell and longer thanthe width Vofthe top wall,`the "box being substantially vcentered transversely on the top 'wall on whichit is supported, rand in whichtheopening in the bottom of the box is elongated inlthe direction of extent of the cell and of a length substantially 'greater than the'width of' the top'wall of the .cell andiofv a width somewhat 1essthan'the width Aofthe topwall 'of the cell on which the box is supported, the opening 'in the 'bottom'of the'box being in register with the opening in the top wall of the cell, 'and thebox'has 'a plurality of "fastening means extending through holes in'itsbottom and adjacent to the elongated opening for connecting the box to the top wall'of the cell. l

2. An underfloor .duct systemincluding cellular vflooring having 'a cell with'an"elongated top wall, ajunction box for'connecting underoor tubularelectric conductor lrousingswith the interior of the cellof said cellular liooring, said box'having sidewalls withopenings therein for receiving the ends of the'conductor housings, and said box "being supported from the top wall of the ycell and having ak generally circular bottom withVv an opening therein for communicatingwi'th'the interior of'a floor cell through'an `opening in the' top `wall ofthe'cell elongated in the direction of the length 'of the cell,-the opening in the bottom rof the box being similarly/elongated to a lengtheequalto almost the'full diameter Yof the bottom-.oflthe box'andhaving a width substantially 'less than the diameter of the bottom and somewhat less-than that of the v top wallof the cell -with Awhich the box is connected,1thefelongated 'opening in the bottom-'ofthe box having edge portions that extend downwardly below the'bottorn-:ofthe box.and'withsrunning clearance through the'opening in the top wall of the cell, the elongated opening in the box having ends of reduced width, and the bottom of-the box having'holes therein atoppositesides-'of the-elongated opening in the box, for receiving fastening Velements thatfconnect the.box1 to .the tloor cell, Vthe holes being spaced. .fromfone-another `by .a

5 transverse distance less than the transverse width across the downwardly extending edge portions of the elongated opening in the box, and said holes being located near the elongated opening and at locations where the opening is of reduced width so as to locate all of said holes over the top of the cell with which the junction box corn-l municates.

3. The underoor duct system described in claim 2, and in which the reduced width of the elongated opening through the bottom of the box consists of rounded ends of the opening and the opening has edge portions that turn downwardly into a substantially vertical direction below the bottom of the box and that project through an opening in the top wall of the cell when the box is in its an angle of at least 90 into a substantially vertical direction at a location below the bottom of the box to provide a guide within the opening through the top wall of the floor cell `for preventing conductors in the oor cell from striking the edges of the opening in the oor cell when the conductors are pulled upwardly from the ooi cell into the junction box.

References Cited in the tile of this patent UNITED STATES PATENTS 788,880 Bossert' May 2, 1905 1,533,759 Richardson et al. Apr. 14, 1925 1,949,883l Sharp Mar. 6, 1934 V2,043,648 Bissell et al. June 9, 1936 2,063,569 Walker Dec. 8, 1936 2,657,250 Wiesmann Oct. 27, 1953 2,735,166 Hoseason Feb. 21, 1956 

